Merge branch 'ps/reftable-backend' into kn/for-all-refs

* ps/reftable-backend:
  refs/reftable: fix leak when copying reflog fails
  ci: add jobs to test with the reftable backend
  refs: introduce reftable backend

.github/workflows/main.yml

@@ -266,6 +266,9 @@ jobs:
           - jobname: linux-sha256
             cc: clang
             pool: ubuntu-latest
+          - jobname: linux-reftable
+            cc: clang
+            pool: ubuntu-latest
           - jobname: linux-gcc
             cc: gcc
             cc_package: gcc-8
@@ -277,6 +280,9 @@ jobs:
           - jobname: osx-clang
             cc: clang
             pool: macos-13
+          - jobname: osx-reftable
+            cc: clang
+            pool: macos-13
           - jobname: osx-gcc
             cc: gcc
             cc_package: gcc-13
@@ -287,6 +293,9 @@ jobs:
           - jobname: linux-leaks
             cc: gcc
             pool: ubuntu-latest
+          - jobname: linux-reftable-leaks
+            cc: gcc
+            pool: ubuntu-latest
           - jobname: linux-asan-ubsan
             cc: clang
             pool: ubuntu-latest

.gitlab-ci.yml

@@ -26,6 +26,9 @@ test:linux:
       - jobname: linux-sha256
         image: ubuntu:latest
         CC: clang
+      - jobname: linux-reftable
+        image: ubuntu:latest
+        CC: clang
       - jobname: linux-gcc
         image: ubuntu:20.04
         CC: gcc
@@ -40,6 +43,9 @@ test:linux:
       - jobname: linux-leaks
         image: ubuntu:latest
         CC: gcc
+      - jobname: linux-reftable-leaks
+        image: ubuntu:latest
+        CC: gcc
       - jobname: linux-asan-ubsan
         image: ubuntu:latest
         CC: clang
@@ -79,6 +85,9 @@ test:osx:
       - jobname: osx-clang
         image: macos-13-xcode-14
         CC: clang
+      - jobname: osx-reftable
+        image: macos-13-xcode-14
+        CC: clang
   artifacts:
     paths:
       - t/failed-test-artifacts

Documentation/ref-storage-format.txt

@@ -1 +1,3 @@
 * `files` for loose files with packed-refs. This is the default.
+* `reftable` for the reftable format. This format is experimental and its
+  internals are subject to change.

Documentation/technical/repository-version.txt

@@ -103,5 +103,6 @@ GIT_COMMON_DIR/worktrees/<id>/config.worktree)
 
 ==== `refStorage`
 
-Specifies the file format for the ref database. The only valid value
-is `files` (loose references with a packed-refs file).
+Specifies the file format for the ref database. The valid values are
+`files` (loose references with a packed-refs file) and `reftable` (see
+Documentation/technical/reftable.txt).

Makefile

@@ -1126,6 +1126,7 @@ LIB_OBJS += reflog.o
 LIB_OBJS += refs.o
 LIB_OBJS += refs/debug.o
 LIB_OBJS += refs/files-backend.o
+LIB_OBJS += refs/reftable-backend.o
 LIB_OBJS += refs/iterator.o
 LIB_OBJS += refs/packed-backend.o
 LIB_OBJS += refs/ref-cache.o

ci/lib.sh

@@ -367,7 +367,7 @@ linux-musl)
 	MAKEFLAGS="$MAKEFLAGS NO_REGEX=Yes ICONV_OMITS_BOM=Yes"
 	MAKEFLAGS="$MAKEFLAGS GIT_TEST_UTF8_LOCALE=C.UTF-8"
 	;;
-linux-leaks)
+linux-leaks|linux-reftable-leaks)
 	export SANITIZE=leak
 	export GIT_TEST_PASSING_SANITIZE_LEAK=true
 	export GIT_TEST_SANITIZE_LEAK_LOG=true

ci/run-build-and-tests.sh

@@ -37,6 +37,9 @@ linux-clang)
 linux-sha256)
 	export GIT_TEST_DEFAULT_HASH=sha256
 	;;
+linux-reftable|linux-reftable-leaks|osx-reftable)
+	export GIT_TEST_DEFAULT_REF_FORMAT=reftable
+	;;
 pedantic)
 	# Don't run the tests; we only care about whether Git can be
 	# built.

contrib/workdir/git-new-workdir

@@ -79,7 +79,7 @@ trap cleanup $siglist
 # create the links to the original repo.  explicitly exclude index, HEAD and
 # logs/HEAD from the list since they are purely related to the current working
 # directory, and should not be shared.
-for x in config refs logs/refs objects info hooks packed-refs remotes rr-cache svn
+for x in config refs logs/refs objects info hooks packed-refs remotes rr-cache svn reftable
 do
 	# create a containing directory if needed
 	case $x in

path.c

@@ -871,7 +871,7 @@ const char *enter_repo(const char *path, int strict)
 	return NULL;
 }
 
-static int calc_shared_perm(int mode)
+int calc_shared_perm(int mode)
 {
 	int tweak;
 

path.h

@@ -181,6 +181,7 @@ const char *git_path_shallow(struct repository *r);
 int ends_with_path_components(const char *path, const char *components);
 int validate_headref(const char *ref);
 
+int calc_shared_perm(int mode);
 int adjust_shared_perm(const char *path);
 
 char *interpolate_path(const char *path, int real_home);

refs.c

@@ -35,6 +35,7 @@
  */
 static const struct ref_storage_be *refs_backends[] = {
 	[REF_STORAGE_FORMAT_FILES] = &refs_be_files,
+	[REF_STORAGE_FORMAT_REFTABLE] = &refs_be_reftable,
 };
 
 static const struct ref_storage_be *find_ref_storage_backend(unsigned int ref_storage_format)

refs/refs-internal.h

@@ -693,6 +693,7 @@ struct ref_storage_be {
 };
 
 extern struct ref_storage_be refs_be_files;
+extern struct ref_storage_be refs_be_reftable;
 extern struct ref_storage_be refs_be_packed;
 
 /*

repository.h

@@ -24,8 +24,9 @@ enum fetch_negotiation_setting {
 	FETCH_NEGOTIATION_NOOP,
 };
 
-#define REF_STORAGE_FORMAT_UNKNOWN 0
-#define REF_STORAGE_FORMAT_FILES   1
+#define REF_STORAGE_FORMAT_UNKNOWN  0
+#define REF_STORAGE_FORMAT_FILES    1
+#define REF_STORAGE_FORMAT_REFTABLE 2
 
 struct repo_settings {
 	int initialized;

t/t0610-reftable-basics.sh

@@ -0,0 +1,887 @@
+#!/bin/sh
+#
+# Copyright (c) 2020 Google LLC
+#
+
+test_description='reftable basics'
+GIT_TEST_DEFAULT_INITIAL_BRANCH_NAME=main
+export GIT_TEST_DEFAULT_INITIAL_BRANCH_NAME
+
+. ./test-lib.sh
+
+if ! test_have_prereq REFTABLE
+then
+	skip_all='skipping reftable tests; set GIT_TEST_DEFAULT_REF_FORMAT=reftable'
+	test_done
+fi
+
+INVALID_OID=$(test_oid 001)
+
+test_expect_success 'init: creates basic reftable structures' '
+	test_when_finished "rm -rf repo" &&
+	git init repo &&
+	test_path_is_dir repo/.git/reftable &&
+	test_path_is_file repo/.git/reftable/tables.list &&
+	echo reftable >expect &&
+	git -C repo rev-parse --show-ref-format >actual &&
+	test_cmp expect actual
+'
+
+test_expect_success 'init: sha256 object format via environment variable' '
+	test_when_finished "rm -rf repo" &&
+	GIT_DEFAULT_HASH=sha256 git init repo &&
+	cat >expect <<-EOF &&
+	sha256
+	reftable
+	EOF
+	git -C repo rev-parse --show-object-format --show-ref-format >actual &&
+	test_cmp expect actual
+'
+
+test_expect_success 'init: sha256 object format via option' '
+	test_when_finished "rm -rf repo" &&
+	git init --object-format=sha256 repo &&
+	cat >expect <<-EOF &&
+	sha256
+	reftable
+	EOF
+	git -C repo rev-parse --show-object-format --show-ref-format >actual &&
+	test_cmp expect actual
+'
+
+test_expect_success 'init: reinitializing reftable backend succeeds' '
+	test_when_finished "rm -rf repo" &&
+	git init repo &&
+	test_commit -C repo A &&
+
+	git -C repo for-each-ref >expect &&
+	git init --ref-format=reftable repo &&
+	git -C repo for-each-ref >actual &&
+	test_cmp expect actual
+'
+
+test_expect_success 'init: reinitializing files with reftable backend fails' '
+	test_when_finished "rm -rf repo" &&
+	git init --ref-format=files repo &&
+	test_commit -C repo file &&
+
+	cp repo/.git/HEAD expect &&
+	test_must_fail git init --ref-format=reftable repo &&
+	test_cmp expect repo/.git/HEAD
+'
+
+test_expect_success 'init: reinitializing reftable with files backend fails' '
+	test_when_finished "rm -rf repo" &&
+	git init --ref-format=reftable repo &&
+	test_commit -C repo file &&
+
+	cp repo/.git/HEAD expect &&
+	test_must_fail git init --ref-format=files repo &&
+	test_cmp expect repo/.git/HEAD
+'
+
+test_expect_perms () {
+	local perms="$1"
+	local file="$2"
+	local actual=$(ls -l "$file") &&
+
+	case "$actual" in
+	$perms*)
+		: happy
+		;;
+	*)
+		echo "$(basename $2) is not $perms but $actual"
+		false
+		;;
+	esac
+}
+
+for umask in 002 022
+do
+	test_expect_success POSIXPERM 'init: honors core.sharedRepository' '
+		test_when_finished "rm -rf repo" &&
+		(
+			umask $umask &&
+			git init --shared=true repo &&
+			test 1 = "$(git -C repo config core.sharedrepository)"
+		) &&
+		test_expect_perms "-rw-rw-r--" repo/.git/reftable/tables.list &&
+		for table in repo/.git/reftable/*.ref
+		do
+			test_expect_perms "-rw-rw-r--" "$table" ||
+			return 1
+		done
+	'
+done
+
+test_expect_success 'clone: can clone reftable repository' '
+	test_when_finished "rm -rf repo clone" &&
+	git init repo &&
+	test_commit -C repo message1 file1 &&
+
+	git clone repo cloned &&
+	echo reftable >expect &&
+	git -C cloned rev-parse --show-ref-format >actual &&
+	test_cmp expect actual &&
+	test_path_is_file cloned/file1
+'
+
+test_expect_success 'clone: can clone reffiles into reftable repository' '
+	test_when_finished "rm -rf reffiles reftable" &&
+	git init --ref-format=files reffiles &&
+	test_commit -C reffiles A &&
+	git clone --ref-format=reftable ./reffiles reftable &&
+
+	git -C reffiles rev-parse HEAD >expect &&
+	git -C reftable rev-parse HEAD >actual &&
+	test_cmp expect actual &&
+
+	git -C reftable rev-parse --show-ref-format >actual &&
+	echo reftable >expect &&
+	test_cmp expect actual &&
+
+	git -C reffiles rev-parse --show-ref-format >actual &&
+	echo files >expect &&
+	test_cmp expect actual
+'
+
+test_expect_success 'clone: can clone reftable into reffiles repository' '
+	test_when_finished "rm -rf reffiles reftable" &&
+	git init --ref-format=reftable reftable &&
+	test_commit -C reftable A &&
+	git clone --ref-format=files ./reftable reffiles &&
+
+	git -C reftable rev-parse HEAD >expect &&
+	git -C reffiles rev-parse HEAD >actual &&
+	test_cmp expect actual &&
+
+	git -C reftable rev-parse --show-ref-format >actual &&
+	echo reftable >expect &&
+	test_cmp expect actual &&
+
+	git -C reffiles rev-parse --show-ref-format >actual &&
+	echo files >expect &&
+	test_cmp expect actual
+'
+
+test_expect_success 'ref transaction: corrupted tables cause failure' '
+	test_when_finished "rm -rf repo" &&
+	git init repo &&
+	(
+		cd repo &&
+		test_commit file1 &&
+		for f in .git/reftable/*.ref
+		do
+			: >"$f" || return 1
+		done &&
+		test_must_fail git update-ref refs/heads/main HEAD
+	)
+'
+
+test_expect_success 'ref transaction: corrupted tables.list cause failure' '
+	test_when_finished "rm -rf repo" &&
+	git init repo &&
+	(
+		cd repo &&
+		test_commit file1 &&
+		echo garbage >.git/reftable/tables.list &&
+		test_must_fail git update-ref refs/heads/main HEAD
+	)
+'
+
+test_expect_success 'ref transaction: refuses to write ref causing F/D conflict' '
+	test_when_finished "rm -rf repo" &&
+	git init repo &&
+	test_commit -C repo file &&
+	test_must_fail git -C repo update-ref refs/heads/main/forbidden
+'
+
+test_expect_success 'ref transaction: deleting ref with invalid name fails' '
+	test_when_finished "rm -rf repo" &&
+	git init repo &&
+	test_commit -C repo file &&
+	test_must_fail git -C repo update-ref -d ../../my-private-file
+'
+
+test_expect_success 'ref transaction: can skip object ID verification' '
+	test_when_finished "rm -rf repo" &&
+	git init repo &&
+	test_must_fail test-tool -C repo ref-store main update-ref msg refs/heads/branch $INVALID_OID $ZERO_OID 0 &&
+	test-tool -C repo ref-store main update-ref msg refs/heads/branch $INVALID_OID $ZERO_OID REF_SKIP_OID_VERIFICATION
+'
+
+test_expect_success 'ref transaction: updating same ref multiple times fails' '
+	test_when_finished "rm -rf repo" &&
+	git init repo &&
+	test_commit -C repo A &&
+	cat >updates <<-EOF &&
+	update refs/heads/main $A
+	update refs/heads/main $A
+	EOF
+	cat >expect <<-EOF &&
+	fatal: multiple updates for ref ${SQ}refs/heads/main${SQ} not allowed
+	EOF
+	test_must_fail git -C repo update-ref --stdin <updates 2>err &&
+	test_cmp expect err
+'
+
+test_expect_success 'ref transaction: can delete symbolic self-reference with git-symbolic-ref(1)' '
+	test_when_finished "rm -rf repo" &&
+	git init repo &&
+	git -C repo symbolic-ref refs/heads/self refs/heads/self &&
+	git -C repo symbolic-ref -d refs/heads/self
+'
+
+test_expect_success 'ref transaction: deleting symbolic self-reference without --no-deref fails' '
+	test_when_finished "rm -rf repo" &&
+	git init repo &&
+	git -C repo symbolic-ref refs/heads/self refs/heads/self &&
+	cat >expect <<-EOF &&
+	error: multiple updates for ${SQ}refs/heads/self${SQ} (including one via symref ${SQ}refs/heads/self${SQ}) are not allowed
+	EOF
+	test_must_fail git -C repo update-ref -d refs/heads/self 2>err &&
+	test_cmp expect err
+'
+
+test_expect_success 'ref transaction: deleting symbolic self-reference with --no-deref succeeds' '
+	test_when_finished "rm -rf repo" &&
+	git init repo &&
+	git -C repo symbolic-ref refs/heads/self refs/heads/self &&
+	git -C repo update-ref -d --no-deref refs/heads/self
+'
+
+test_expect_success 'ref transaction: creating symbolic ref fails with F/D conflict' '
+	test_when_finished "rm -rf repo" &&
+	git init repo &&
+	test_commit -C repo A &&
+	cat >expect <<-EOF &&
+	error: unable to write symref for refs/heads: file/directory conflict
+	EOF
+	test_must_fail git -C repo symbolic-ref refs/heads refs/heads/foo 2>err &&
+	test_cmp expect err
+'
+
+test_expect_success 'ref transaction: ref deletion' '
+	test_when_finished "rm -rf repo" &&
+	git init repo &&
+	(
+		cd repo &&
+		test_commit file &&
+		HEAD_OID=$(git show-ref -s --verify HEAD) &&
+		cat >expect <<-EOF &&
+		$HEAD_OID refs/heads/main
+		$HEAD_OID refs/tags/file
+		EOF
+		git show-ref >actual &&
+		test_cmp expect actual &&
+
+		test_must_fail git update-ref -d refs/tags/file $INVALID_OID &&
+		git show-ref >actual &&
+		test_cmp expect actual &&
+
+		git update-ref -d refs/tags/file $HEAD_OID &&
+		echo "$HEAD_OID refs/heads/main" >expect &&
+		git show-ref >actual &&
+		test_cmp expect actual
+	)
+'
+
+test_expect_success 'ref transaction: writes cause auto-compaction' '
+	test_when_finished "rm -rf repo" &&
+
+	git init repo &&
+	test_line_count = 1 repo/.git/reftable/tables.list &&
+
+	test_commit -C repo --no-tag A &&
+	test_line_count = 2 repo/.git/reftable/tables.list &&
+
+	test_commit -C repo --no-tag B &&
+	test_line_count = 1 repo/.git/reftable/tables.list
+'
+
+check_fsync_events () {
+	local trace="$1" &&
+	shift &&
+
+	cat >expect &&
+	sed -n \
+		-e '/^{"event":"counter",.*"category":"fsync",/ {
+			s/.*"category":"fsync",//;
+			s/}$//;
+			p;
+		}' \
+		<"$trace" >actual &&
+	test_cmp expect actual
+}
+
+test_expect_success 'ref transaction: writes are synced' '
+	test_when_finished "rm -rf repo" &&
+	git init repo &&
+	test_commit -C repo initial &&
+
+	GIT_TRACE2_EVENT="$(pwd)/trace2.txt" \
+	GIT_TEST_FSYNC=true \
+		git -C repo -c core.fsync=reference \
+		-c core.fsyncMethod=fsync update-ref refs/heads/branch HEAD &&
+	check_fsync_events trace2.txt <<-EOF
+	"name":"hardware-flush","count":2
+	EOF
+'
+
+test_expect_success 'pack-refs: compacts tables' '
+	test_when_finished "rm -rf repo" &&
+	git init repo &&
+
+	test_commit -C repo A &&
+	ls -1 repo/.git/reftable >table-files &&
+	test_line_count = 4 table-files &&
+	test_line_count = 3 repo/.git/reftable/tables.list &&
+
+	git -C repo pack-refs &&
+	ls -1 repo/.git/reftable >table-files &&
+	test_line_count = 2 table-files &&
+	test_line_count = 1 repo/.git/reftable/tables.list
+'
+
+test_expect_success 'pack-refs: prunes stale tables' '
+	test_when_finished "rm -rf repo" &&
+	git init repo &&
+	touch repo/.git/reftable/stale-table.ref &&
+	git -C repo pack-refs &&
+	test_path_is_missing repo/.git/reftable/stable-ref.ref
+'
+
+test_expect_success 'pack-refs: does not prune non-table files' '
+	test_when_finished "rm -rf repo" &&
+	git init repo &&
+	touch repo/.git/reftable/garbage &&
+	git -C repo pack-refs &&
+	test_path_is_file repo/.git/reftable/garbage
+'
+
+for umask in 002 022
+do
+	test_expect_success POSIXPERM 'pack-refs: honors core.sharedRepository' '
+		test_when_finished "rm -rf repo" &&
+		(
+			umask $umask &&
+			git init --shared=true repo &&
+			test_commit -C repo A &&
+			test_line_count = 3 repo/.git/reftable/tables.list
+		) &&
+		git -C repo pack-refs &&
+		test_expect_perms "-rw-rw-r--" repo/.git/reftable/tables.list &&
+		for table in repo/.git/reftable/*.ref
+		do
+			test_expect_perms "-rw-rw-r--" "$table" ||
+			return 1
+		done
+	'
+done
+
+test_expect_success 'packed-refs: writes are synced' '
+	test_when_finished "rm -rf repo" &&
+	git init repo &&
+	test_commit -C repo initial &&
+	test_line_count = 2 table-files &&
+
+	: >trace2.txt &&
+	GIT_TRACE2_EVENT="$(pwd)/trace2.txt" \
+	GIT_TEST_FSYNC=true \
+		git -C repo -c core.fsync=reference \
+		-c core.fsyncMethod=fsync pack-refs &&
+	check_fsync_events trace2.txt <<-EOF
+	"name":"hardware-flush","count":2
+	EOF
+'
+
+test_expect_success 'ref iterator: bogus names are flagged' '
+	test_when_finished "rm -rf repo" &&
+	git init repo &&
+	(
+		cd repo &&
+		test_commit --no-tag file &&
+		test-tool ref-store main update-ref msg "refs/heads/bogus..name" $(git rev-parse HEAD) $ZERO_OID REF_SKIP_REFNAME_VERIFICATION &&
+
+		cat >expect <<-EOF &&
+		$ZERO_OID refs/heads/bogus..name 0xc
+		$(git rev-parse HEAD) refs/heads/main 0x0
+		EOF
+		test-tool ref-store main for-each-ref "" >actual &&
+		test_cmp expect actual
+	)
+'
+
+test_expect_success 'ref iterator: missing object IDs are not flagged' '
+	test_when_finished "rm -rf repo" &&
+	git init repo &&
+	(
+		cd repo &&
+		test-tool ref-store main update-ref msg "refs/heads/broken-hash" $INVALID_OID $ZERO_OID REF_SKIP_OID_VERIFICATION &&
+
+		cat >expect <<-EOF &&
+		$INVALID_OID refs/heads/broken-hash 0x0
+		EOF
+		test-tool ref-store main for-each-ref "" >actual &&
+		test_cmp expect actual
+	)
+'
+
+test_expect_success 'basic: commit and list refs' '
+	test_when_finished "rm -rf repo" &&
+	git init repo &&
+	test_commit -C repo file &&
+	test_write_lines refs/heads/main refs/tags/file >expect &&
+	git -C repo for-each-ref --format="%(refname)" >actual &&
+	test_cmp actual expect
+'
+
+test_expect_success 'basic: can write large commit message' '
+	test_when_finished "rm -rf repo" &&
+	git init repo &&
+	perl -e "
+		print \"this is a long commit message\" x 50000
+	" >commit-msg &&
+	git -C repo commit --allow-empty --file=../commit-msg
+'
+
+test_expect_success 'basic: show-ref fails with empty repository' '
+	test_when_finished "rm -rf repo" &&
+	git init repo &&
+	test_must_fail git -C repo show-ref >actual &&
+	test_must_be_empty actual
+'
+
+test_expect_success 'basic: can check out unborn branch' '
+	test_when_finished "rm -rf repo" &&
+	git init repo &&
+	git -C repo checkout -b main
+'
+
+test_expect_success 'basic: peeled tags are stored' '
+	test_when_finished "rm -rf repo" &&
+	git init repo &&
+	test_commit -C repo file &&
+	git -C repo tag -m "annotated tag" test_tag HEAD &&
+	for ref in refs/heads/main refs/tags/file refs/tags/test_tag refs/tags/test_tag^{}
+	do
+		echo "$(git -C repo rev-parse "$ref") $ref" || return 1
+	done >expect &&
+	git -C repo show-ref -d >actual &&
+	test_cmp expect actual
+'
+
+test_expect_success 'basic: for-each-ref can print symrefs' '
+	test_when_finished "rm -rf repo" &&
+	git init repo &&
+	(
+		cd repo &&
+		test_commit file &&
+		git branch &&
+		git symbolic-ref refs/heads/sym refs/heads/main &&
+		cat >expected <<-EOF &&
+		refs/heads/main
+		EOF
+		git for-each-ref --format="%(symref)" refs/heads/sym >actual &&
+		test_cmp expected actual
+	)
+'
+
+test_expect_success 'basic: notes' '
+	test_when_finished "rm -rf repo" &&
+	git init repo &&
+	(
+		write_script fake_editor <<-\EOF &&
+		echo "$MSG" >"$1"
+		echo "$MSG" >&2
+		EOF
+
+		test_commit 1st &&
+		test_commit 2nd &&
+		GIT_EDITOR=./fake_editor MSG=b4 git notes add &&
+		GIT_EDITOR=./fake_editor MSG=b3 git notes edit &&
+		echo b4 >expect &&
+		git notes --ref commits@{1} show >actual &&
+		test_cmp expect actual
+	)
+'
+
+test_expect_success 'basic: stash' '
+	test_when_finished "rm -rf repo" &&
+	git init repo &&
+	(
+		cd repo &&
+		test_commit file &&
+		git stash list >expect &&
+		test_line_count = 0 expect &&
+
+		echo hoi >>file.t &&
+		git stash push -m stashed &&
+		git stash list >expect &&
+		test_line_count = 1 expect &&
+
+		git stash clear &&
+		git stash list >expect &&
+		test_line_count = 0 expect
+	)
+'
+
+test_expect_success 'basic: cherry-pick' '
+	test_when_finished "rm -rf repo" &&
+	git init repo &&
+	(
+		cd repo &&
+		test_commit message1 file1 &&
+		test_commit message2 file2 &&
+		git branch source &&
+		git checkout HEAD^ &&
+		test_commit message3 file3 &&
+		git cherry-pick source &&
+		test_path_is_file file2
+	)
+'
+
+test_expect_success 'basic: rebase' '
+	test_when_finished "rm -rf repo" &&
+	git init repo &&
+	(
+		cd repo &&
+		test_commit message1 file1 &&
+		test_commit message2 file2 &&
+		git branch source &&
+		git checkout HEAD^ &&
+		test_commit message3 file3 &&
+		git rebase source &&
+		test_path_is_file file2
+	)
+'
+
+test_expect_success 'reflog: can delete separate reflog entries' '
+	test_when_finished "rm -rf repo" &&
+	git init repo &&
+	(
+		cd repo &&
+
+		test_commit file &&
+		test_commit file2 &&
+		test_commit file3 &&
+		test_commit file4 &&
+		git reflog >actual &&
+		grep file3 actual &&
+
+		git reflog delete HEAD@{1} &&
+		git reflog >actual &&
+		! grep file3 actual
+	)
+'
+
+test_expect_success 'reflog: can switch to previous branch' '
+	test_when_finished "rm -rf repo" &&
+	git init repo &&
+	(
+		cd repo &&
+		test_commit file1 &&
+		git checkout -b branch1 &&
+		test_commit file2 &&
+		git checkout -b branch2 &&
+		git switch - &&
+		git rev-parse --symbolic-full-name HEAD >actual &&
+		echo refs/heads/branch1 >expect &&
+		test_cmp actual expect
+	)
+'
+
+test_expect_success 'reflog: copying branch writes reflog entry' '
+	test_when_finished "rm -rf repo" &&
+	git init repo &&
+	(
+		cd repo &&
+		test_commit file1 &&
+		test_commit file2 &&
+		oid=$(git rev-parse --short HEAD) &&
+		git branch src &&
+		cat >expect <<-EOF &&
+		${oid} dst@{0}: Branch: copied refs/heads/src to refs/heads/dst
+		${oid} dst@{1}: branch: Created from main
+		EOF
+		git branch -c src dst &&
+		git reflog dst >actual &&
+		test_cmp expect actual
+	)
+'
+
+test_expect_success 'reflog: renaming branch writes reflog entry' '
+	test_when_finished "rm -rf repo" &&
+	git init repo &&
+	(
+		cd repo &&
+		git symbolic-ref HEAD refs/heads/before &&
+		test_commit file &&
+		git show-ref >expected.refs &&
+		sed s/before/after/g <expected.refs >expected &&
+		git branch -M after &&
+		git show-ref >actual &&
+		test_cmp expected actual &&
+		echo refs/heads/after >expected &&
+		git symbolic-ref HEAD >actual &&
+		test_cmp expected actual
+	)
+'
+
+test_expect_success 'reflog: can store empty logs' '
+	test_when_finished "rm -rf repo" &&
+	git init repo &&
+	(
+		cd repo &&
+
+		test_must_fail test-tool ref-store main reflog-exists refs/heads/branch &&
+		test-tool ref-store main create-reflog refs/heads/branch &&
+		test-tool ref-store main reflog-exists refs/heads/branch &&
+		test-tool ref-store main for-each-reflog-ent-reverse refs/heads/branch >actual &&
+		test_must_be_empty actual
+	)
+'
+
+test_expect_success 'reflog: expiry empties reflog' '
+	test_when_finished "rm -rf repo" &&
+	git init repo &&
+	(
+		cd repo &&
+
+		test_commit initial &&
+		git checkout -b branch &&
+		test_commit fileA &&
+		test_commit fileB &&
+
+		cat >expect <<-EOF &&
+		commit: fileB
+		commit: fileA
+		branch: Created from HEAD
+		EOF
+		git reflog show --format="%gs" refs/heads/branch >actual &&
+		test_cmp expect actual &&
+
+		git reflog expire branch --expire=all &&
+		git reflog show --format="%gs" refs/heads/branch >actual &&
+		test_must_be_empty actual &&
+		test-tool ref-store main reflog-exists refs/heads/branch
+	)
+'
+
+test_expect_success 'reflog: can be deleted' '
+	test_when_finished "rm -rf repo" &&
+	git init repo &&
+	(
+		cd repo &&
+		test_commit initial &&
+		test-tool ref-store main reflog-exists refs/heads/main &&
+		test-tool ref-store main delete-reflog refs/heads/main &&
+		test_must_fail test-tool ref-store main reflog-exists refs/heads/main
+	)
+'
+
+test_expect_success 'reflog: garbage collection deletes reflog entries' '
+	test_when_finished "rm -rf repo" &&
+	git init repo &&
+	(
+		cd repo &&
+
+		for count in $(test_seq 1 10)
+		do
+			test_commit "number $count" file.t $count number-$count ||
+			return 1
+		done &&
+		git reflog refs/heads/main >actual &&
+		test_line_count = 10 actual &&
+		grep "commit (initial): number 1" actual &&
+		grep "commit: number 10" actual &&
+
+		git gc &&
+		git reflog refs/heads/main >actual &&
+		test_line_count = 0 actual
+	)
+'
+
+test_expect_success 'reflog: updates via HEAD update HEAD reflog' '
+	test_when_finished "rm -rf repo" &&
+	git init repo &&
+	(
+		cd repo &&
+		test_commit main-one &&
+		git checkout -b new-branch &&
+		test_commit new-one &&
+		test_commit new-two &&
+
+		echo new-one >expect &&
+		git log -1 --format=%s HEAD@{1} >actual &&
+		test_cmp expect actual
+	)
+'
+
+test_expect_success 'worktree: adding worktree creates separate stack' '
+	test_when_finished "rm -rf repo worktree" &&
+	git init repo &&
+	test_commit -C repo A &&
+
+	git -C repo worktree add ../worktree &&
+	test_path_is_file repo/.git/worktrees/worktree/refs/heads &&
+	echo "ref: refs/heads/.invalid" >expect &&
+	test_cmp expect repo/.git/worktrees/worktree/HEAD &&
+	test_path_is_dir repo/.git/worktrees/worktree/reftable &&
+	test_path_is_file repo/.git/worktrees/worktree/reftable/tables.list
+'
+
+test_expect_success 'worktree: pack-refs in main repo packs main refs' '
+	test_when_finished "rm -rf repo worktree" &&
+	git init repo &&
+	test_commit -C repo A &&
+	git -C repo worktree add ../worktree &&
+
+	test_line_count = 3 repo/.git/worktrees/worktree/reftable/tables.list &&
+	test_line_count = 4 repo/.git/reftable/tables.list &&
+	git -C repo pack-refs &&
+	test_line_count = 3 repo/.git/worktrees/worktree/reftable/tables.list &&
+	test_line_count = 1 repo/.git/reftable/tables.list
+'
+
+test_expect_success 'worktree: pack-refs in worktree packs worktree refs' '
+	test_when_finished "rm -rf repo worktree" &&
+	git init repo &&
+	test_commit -C repo A &&
+	git -C repo worktree add ../worktree &&
+
+	test_line_count = 3 repo/.git/worktrees/worktree/reftable/tables.list &&
+	test_line_count = 4 repo/.git/reftable/tables.list &&
+	git -C worktree pack-refs &&
+	test_line_count = 1 repo/.git/worktrees/worktree/reftable/tables.list &&
+	test_line_count = 4 repo/.git/reftable/tables.list
+'
+
+test_expect_success 'worktree: creating shared ref updates main stack' '
+	test_when_finished "rm -rf repo worktree" &&
+	git init repo &&
+	test_commit -C repo A &&
+
+	git -C repo worktree add ../worktree &&
+	git -C repo pack-refs &&
+	git -C worktree pack-refs &&
+	test_line_count = 1 repo/.git/worktrees/worktree/reftable/tables.list &&
+	test_line_count = 1 repo/.git/reftable/tables.list &&
+
+	git -C worktree update-ref refs/heads/shared HEAD &&
+	test_line_count = 1 repo/.git/worktrees/worktree/reftable/tables.list &&
+	test_line_count = 2 repo/.git/reftable/tables.list
+'
+
+test_expect_success 'worktree: creating per-worktree ref updates worktree stack' '
+	test_when_finished "rm -rf repo worktree" &&
+	git init repo &&
+	test_commit -C repo A &&
+
+	git -C repo worktree add ../worktree &&
+	git -C repo pack-refs &&
+	git -C worktree pack-refs &&
+	test_line_count = 1 repo/.git/worktrees/worktree/reftable/tables.list &&
+	test_line_count = 1 repo/.git/reftable/tables.list &&
+
+	git -C worktree update-ref refs/bisect/per-worktree HEAD &&
+	test_line_count = 2 repo/.git/worktrees/worktree/reftable/tables.list &&
+	test_line_count = 1 repo/.git/reftable/tables.list
+'
+
+test_expect_success 'worktree: creating per-worktree ref from main repo' '
+	test_when_finished "rm -rf repo worktree" &&
+	git init repo &&
+	test_commit -C repo A &&
+
+	git -C repo worktree add ../worktree &&
+	git -C repo pack-refs &&
+	git -C worktree pack-refs &&
+	test_line_count = 1 repo/.git/worktrees/worktree/reftable/tables.list &&
+	test_line_count = 1 repo/.git/reftable/tables.list &&
+
+	git -C repo update-ref worktrees/worktree/refs/bisect/per-worktree HEAD &&
+	test_line_count = 2 repo/.git/worktrees/worktree/reftable/tables.list &&
+	test_line_count = 1 repo/.git/reftable/tables.list
+'
+
+test_expect_success 'worktree: creating per-worktree ref from second worktree' '
+	test_when_finished "rm -rf repo wt1 wt2" &&
+	git init repo &&
+	test_commit -C repo A &&
+
+	git -C repo worktree add ../wt1 &&
+	git -C repo worktree add ../wt2 &&
+	git -C repo pack-refs &&
+	git -C wt1 pack-refs &&
+	git -C wt2 pack-refs &&
+	test_line_count = 1 repo/.git/worktrees/wt1/reftable/tables.list &&
+	test_line_count = 1 repo/.git/worktrees/wt2/reftable/tables.list &&
+	test_line_count = 1 repo/.git/reftable/tables.list &&
+
+	git -C wt1 update-ref worktrees/wt2/refs/bisect/per-worktree HEAD &&
+	test_line_count = 1 repo/.git/worktrees/wt1/reftable/tables.list &&
+	test_line_count = 2 repo/.git/worktrees/wt2/reftable/tables.list &&
+	test_line_count = 1 repo/.git/reftable/tables.list
+'
+
+test_expect_success 'worktree: can create shared and per-worktree ref in one transaction' '
+	test_when_finished "rm -rf repo worktree" &&
+	git init repo &&
+	test_commit -C repo A &&
+
+	git -C repo worktree add ../worktree &&
+	git -C repo pack-refs &&
+	git -C worktree pack-refs &&
+	test_line_count = 1 repo/.git/worktrees/worktree/reftable/tables.list &&
+	test_line_count = 1 repo/.git/reftable/tables.list &&
+
+	cat >stdin <<-EOF &&
+	create worktrees/worktree/refs/bisect/per-worktree HEAD
+	create refs/branches/shared HEAD
+	EOF
+	git -C repo update-ref --stdin <stdin &&
+	test_line_count = 2 repo/.git/worktrees/worktree/reftable/tables.list &&
+	test_line_count = 2 repo/.git/reftable/tables.list
+'
+
+test_expect_success 'worktree: can access common refs' '
+	test_when_finished "rm -rf repo worktree" &&
+	git init repo &&
+	test_commit -C repo file1 &&
+	git -C repo branch branch1 &&
+	git -C repo worktree add ../worktree &&
+
+	echo refs/heads/worktree >expect &&
+	git -C worktree symbolic-ref HEAD >actual &&
+	test_cmp expect actual &&
+	git -C worktree checkout branch1
+'
+
+test_expect_success 'worktree: adds worktree with detached HEAD' '
+	test_when_finished "rm -rf repo worktree" &&
+
+	git init repo &&
+	test_commit -C repo A &&
+	git -C repo rev-parse main >expect &&
+
+	git -C repo worktree add --detach ../worktree main &&
+	git -C worktree rev-parse HEAD >actual &&
+	test_cmp expect actual
+'
+
+test_expect_success 'fetch: accessing FETCH_HEAD special ref works' '
+	test_when_finished "rm -rf repo sub" &&
+
+	git init sub &&
+	test_commit -C sub two &&
+	git -C sub rev-parse HEAD >expect &&
+
+	git init repo &&
+	test_commit -C repo one &&
+	git -C repo fetch ../sub &&
+	git -C repo rev-parse FETCH_HEAD >actual &&
+	test_cmp expect actual
+'
+
+test_done

t/t0611-reftable-httpd.sh

@@ -0,0 +1,26 @@
+#!/bin/sh
+
+test_description='reftable HTTPD tests'
+
+. ./test-lib.sh
+. "$TEST_DIRECTORY"/lib-httpd.sh
+
+start_httpd
+
+REPO="$HTTPD_DOCUMENT_ROOT_PATH/repo"
+
+test_expect_success 'serving ls-remote' '
+	git init --ref-format=reftable -b main "$REPO" &&
+	cd "$REPO" &&
+	test_commit m1 &&
+	>.git/git-daemon-export-ok &&
+	git ls-remote "http://127.0.0.1:$LIB_HTTPD_PORT/smart/repo" | cut -f 2-2 -d "	" >actual &&
+	cat >expect <<-EOF &&
+	HEAD
+	refs/heads/main
+	refs/tags/m1
+	EOF
+	test_cmp actual expect
+'
+
+test_done

t/test-lib.sh

@@ -1755,6 +1755,8 @@ esac
 case "$GIT_DEFAULT_REF_FORMAT" in
 files)
 	test_set_prereq REFFILES;;
+reftable)
+	test_set_prereq REFTABLE;;
 *)
 	echo 2>&1 "error: unknown ref format $GIT_DEFAULT_REF_FORMAT"
 	exit 1